How did I come to the ALTER USER RENAME command? Just a lucky punch due to my customer. My customer were trying to rename an user in an Oracle Database with several objects (tables, view, functions, types and so) by simply updating the sys.user$ table :-)
The result were better than expected, just synonyms had to be recreated, but a function which is referencing a type caused some problems thats leads to an undocumented ORA-00600.

So I was starting to do some searches in My Oracle Support and finally came across the My Oracle Support Note 10217802.8

Its simply a Bug summing up for a discovered ORA-4030 errors message for the command "ALTER USER .. RENAME". Quick check in the official SQL Language Reference Guides, shows clearly there is no "ALTER USER RENAME" option. So whats going on here? Next search in My Oracle Support with simply the search string "10217802" brings up some Patches for the Bug

Patches for a non-existing feature sounds really interesting :-) when you check out the patches, you will see that the patches were created 10th November 2010 !!!!

So since more than 5 years the really cool feature is existing, but nowhere really described.

What I discover so far:

Users which are holding TABLES, VIEWS, FUNCTIONS, PROCEDURES can be renamed without any problems

Even GRANTS will be transferred correctly :-)

Problems I discovered so far with TYPES and SYNONYMS

SYNONYM owner will be switched correctly, but the table_owner stays untouched, so the synonym will point to an invalid reference. Not nice, but its ok

The fact that a certain fix for an undocumented feature is included in a bundle patch such a PSU does not make it official at all. The only official and supported features are those present in the documentation.